In the railway industry, blue flags are typically portable devices that clip on or clamp on to the rails of a railway track. These devices are heavy and have a large metal flag attached to them that is troublesome in its conventional design. Blue flags are one example of blue signals used in the railway industry. A blue signal is, by definition, a clearly distinguishable blue flag, blue light or blue tag by day or blue light or blue tag by night. When displayed it signifies that workers are on, under or beneath equipment on the rails of a section of railway track.
Some of the problems associated with conventional blue flag designs are associated with wind forces acting on the flag as the force can be considerable due to the size of the flag, thereby pulling someone off balance or blowing the flag out of someone's hands. Blue flags are often carried long distances to where they are needed. When railroads have tried to make these flags out of plastic to reduce the weight, they tend to break easily. Most portable blue flags are lost, broken or needing repair in a short period of time, making them costly safety items. Some attempts have been made to apply permanent blue flags that lay down in the centre of the tracks. These flags have a post with a hinge attached to a railroad tie and accordingly when needed, the flag is lifted from the centre of the track and locked in place vertically. The problem with these flags is that snow covers them in the winter, low riding locomotives rip them out, snow clearing equipment further damages them and oil and grease from locomotives make them dirty, thus requiring cleaning.
U.S. Pat. No. 418,155 to Berry, U.S. Pat. No. 822,195 to Eaton, U.S. Pat. No. 606,197 to Dunn, U.S. Pat. No. 1,297,521 to Van Dresar, U.S. Pat. No. 5,905,216 to Davis and U.S. Pat. No. 6,386,492 to Brown et al as well as Canadian documents 2,265,253 to Davis and U.S. Pat. No. 2,011,942 to Dean et al disclose numerous variations to indicator devices for use with railways. In each instance however removable flags are disclosed which require clamping to the rail resulting in a structure which is readily susceptible to damage and to being lost for reasons noted above.